Vegetable papain consists of several proteolytic enzymes, whose specific action is the hydrolysis of proteins, producing low molecular weight peptides.
As it is known, the enzymes are catalysts that are extremely active in biological reactions and belong to the chemical category of proteins, with chemical groups that can be of a non-protein nature (apoenzyme, the protein part; coenzyme, the non-protein component, especially vitamins and metals).
The enzymes have the character of specificity, and are named on the basis of the substrate on which they act.
The active site of an enzyme consists of a group of amino acids, which are not necessarily positioned in sequence on the polypeptide chain.
The amino acids are essential for human beings, as they make up the sequences of the proteins, as well as of non-protein peptides.
The amino acids are used by cells as nutrients, and are the basis of fundamental physiological activities. They are molecules that contain a COOH— group and an amino group NH2—, joined to one and the same carbon atom C, the alpha carbon with respect to the carboxyl.
With respect to amino acids, the proteins are polymers of condensation of L,alpha amino acids, joined together in long chains by peptide bonds, with a number of proteins that can be extremely large, with L,alpha amino acids combined in various configurations: unknown, with polypeptide chains of helical shape, with folding of the helices with participation of hydrogen bridges.
About 22 amino acids are present in the human body: 8 of these are considered essential, so defined because they are not produced by the human body, but are only obtained from the diet.
Vegetable papain can be considered to be derived from complexes of amino acids with sequences characteristic of papain: lysine, threonine, valine, thionine, leucine, isoleucine, phenylalanine, histidine, arginine, oxyproline, aspartic acid, serine, glutamic acid, proline, alanine, cystine, tyrosine and others.
In the unripe, acidic fruit of Carica papaya there are 20 of the 22 amino acids, including 7 of the 8 regarded as essential. The phenylalanine contained in Carica papaya is among the precursors of substances with antidepressant action. These elementary amino acids can then naturally give rise to an enormous number of amino acid complexes of high molecular weight that are derived from individual amino acids by interaction of various forces: van der Waals, dipole-dipole interactions, particularly hydrogen bonds, ionic bonds.